having a full time job and trying to launch a freelance career is not easy. its simpler to save up money and take a few months off work and work on your freelance projects like crazy. no matter how simple and mundane your regular job is as a human being you cannot realistically work for so long and expect to have a fresh state of mind to work on other projects and produce 100% quality outcome efficiently. talking from my own experience.
I agree, having a full time job and a freelance career is not easy. Having also done this myself, I always felt somewhat guilty about moonlighting. Once you decide you want to go freelance, my advice would be to start saving money so you can get a 3 - 6 months "salary" saved up, and during that time start trying to line up work and get your portfolio ready to go.
